You can find more moon phase details on both of the websites used in this post by clicking on each hyperlink.

Source: nineplanets.org

…

The Moon phase for December 31st, 2025 is a Waxing Gibbous phase. This is the phase where the moon is more than 50% illuminated but has not yet reached 100% illumination (which would be a Full Moon).

In the Northern Hemisphere, the right side will be illuminated, and in the Southern hemisphere it’ll be the left side that is illuminated.

The Waxing Gibbous phase, like all moon phases, will last for just over 7 days. The actual length will vary because of the elliptical shaped orbit of the moon. During this Waxing Gibbous phase the moon will rise in the east in the mid- to late-afternoon and will be high in the eastern sky at sunset.

Assuming it’s a clear night, the Waxing Gibbous moon will then be visible through most of the night before setting just before sunrise.

Fun fact:

Phase Details

Phase: Waxing Gibbous

Moon age: 11.35 days

Moon illumination: 88.93%

Moon tilt: 123.014°

Moon angle: 0.55

Moon distance: 361,650.56 km

Moon sign: Gemini

Source: MoonGiant.com

You can use this link to go forward or backward in time for Moon phase information. If you are curious, you can even find out what phase the Moon was in when you or anyone else was born.

…

Visit the December 2025 Moon Phases Calendar to see all the daily moon phase for this month.

Today’s Waxing Gibbous Phase

The Waxing Gibbous on December 31 has an illumination of 90%. This is the percentage of the Moon illuminated by the Sun. The illumination is constantly changing and can vary up to 10% a day. On December 31 the Moon is 11.71 days old. This refers to how many days it has been since the last New Moon. It takes 29.53 days for the Moon to orbit the Earth and go through the lunar cycle of all 8 Moon phases.

Phase Details